coolant dilemma, its a mystery.

Well after an afternoon of problem solving and trying to figure out why my engine was overheating iv came to the conclusion that I have no idea where the problem is coming from. There was plenty coolant in the car when it started to overheat and the heaters being ice cold lead me to believe it my be an air lock. Iv tried everything filling all the hoses, thermostat housing, parking up hill to bleed it, yet still no heat coming though and still overheating. If I pull off the hose ontop of the waterpump or any of the hoses eventually water splutters out rather than flows. Could it be the water pump has died? With all hoses on and expansion tank cap off it just sits and bubbles. Anyone have any idea? Oh and its on a disco1 300tdi.

Could be pump.or head gasket

Isn't the fill level of the expansion tank above the waterpump? Have you checked that the thermostat opens?

I've not checked that pan of boiling water is next, but if the thermastat was broken would that effect fluid getting through the heater matrix. Also just noticed water dripping from the bad join where my decat is and condensation in exhaust fumes. Looking more like a head gasket problem but still doesn't explain why no fluid getting to heater matrix and is spluttering normal or should it be a flow of water from the pump.

I should think the thermostat is stuck shut as it only lets the hot water through when it opens, i would do that first as it the easiest to do then see if the problem persists

Hi It sounds like the head gasket is on its way out. The same thing happened to a mates disco, no heat from blowers, losing coolant. I you are getting air bubbles in the expansion tank it will almost certainly be coming from a failing head gasket.
Good news. If you have some tools it is not too bad a job as long as you work methodically.

The V8 man said:

I should think the thermostat is stuck shut as it only lets the hot water through when it opens, i would do that first as it the easiest to do then see if the problem persists

Click to expand...

Pop out the little toggle pin, it will allow a little more water through before it opens, even if it is working at the correct temp.

Diggy569 said:

I've not checked that pan of boiling water is next, but if the thermastat was broken would that effect fluid getting through the heater matrix. Also just noticed water dripping from the bad join where my decat is and condensation in exhaust fumes. Looking more like a head gasket problem but still doesn't explain why no fluid getting to heater matrix and is spluttering normal or should it be a flow of water from the pump.

Click to expand...

That is strange that u don't have coolant flowing through the matrix.
Your heater temps is not dependant on the thermostat being open, 300 series have an air blending system so as soon as the temp of the coolant rises so does the heat from the heater matrix.

discool said:

That is strange that u don't have coolant flowing through the matrix.
Your heater temps is not dependant on the thermostat being open, 300 series have an air blending system so as soon as the temp of the coolant rises so does the heat from the heater matrix.

Click to expand...

Last week I lost all hot air from the heaters so thought it must have ran out of coolant but pulling out a busy junction with higher revs made the air turn hot and normal again with no loss of coolant.

Searching the forum it's looking more like the head gasket could be failing or failed and the possibility of a cracked head. Tomorrow ill test the thermostat and check the water pump is still in one piece.

With the water pump it can leak past the shaft seal, that's easy to see, the bearing can fail but you will hear that just like jf the impeller detached from the shaft which is rare

Well after stripping down the head and hoping to see obvious falure it didnt look too bad. Cant see any cracks on the head and gasket didnt look to bad. Only one bit of damage to the gasket by looks of things. Would this cause my problem

Also what are these found them just sitting on piston 3 when I removed the head.

Valve caps, sit on top of the stem under the tappet

blue beasty said:

Valve caps, sit on top of the stem under the rocker arm / tappet

Click to expand...

Thanks guys. Lets hope I didnt loose any other ones in the process of pulling it out.

Diggy569 said:

Thanks guys. Lets hope I didnt loose any other ones in the process of pulling it out.

Click to expand...

If they are worn / missing an easy replacement

Looks as if I've found the fault, missed this on first inspection.
New head it is then anyone got any lying about!

Well tonight I replaced the head, Waterpump and P gasket also a new thermostate and just a quick test before bed resulted in still no heat in heaters! got upto temp pretty quick,once id stopped there with still loads of pressure in expansion tank but no bubbling or exhaust fumes coming through like before.
I did remove the thermostate breather after and the housing was about half full, should it have been properly full at this point?.

Anyone?